Postby oldeskewltoy » Tue Dec 20, 2016 8:49 am
$2500 is a good/quality rebuild*, with a set of cams.
* - rebuild: complete dismantle, clean (@ the machine shop) and check all parts for re-usability, machining time, replacing all wear, or worn items as needed.
Typical wear items: engine bearings (main, and rod - typically about $100-$200 depending on brand used), piston rings (about $125), gaskets and seals($225+ for OEM - others available with varying rates of success). Timing belt and tensioner - $75+. Since your engine has a bad knock, I'd also plan on a new oil pump as well, for the oil your engine may have been ingesting may have bearing material and caused wear.
Now would also be a good time to replace cooling hoses and checking other wear items too - water pump comes to mind.
OEM 4AGE pistons are not as strong as aftermarket, BUT they have worked perfectly fine in many 4AGE engines for hundreds, of thousands of miles - you DON'T have to buy expensive pistons to get a decent build/power.
Find a machine shop who can work on a 4AGE (smaller engines - not all machine shops can work effectively on this engine)
Ok... now as far as a performance boost goes... the very first thing I'd recommend is planning on a compression rise. The original 9.4:1 compression ratio is just too weak to allow other mods to achieve their best results. Plan on a minimum of 10:1, if you are keeping the stock cams, and a minimum of 10.5 for a MILD(214 degree @ .050" lift) cam. As you look at different cams, the longer the duration, the more static compression you will need for them to operate correctly.
Camshafts: You are going to see a lot and hear a lot.... Some basic camshaft info - the stock 16V engines had 2 camshaft offerings, 240(204 @ .050"), with 7.5mm lift, and a 232(198@ .050") with 7mm of lift. The more duration you add, the longer the valve is open (AND conversely the shorter it is closed) this lengthening of duration allows some of the compression to escape, so typically you add more compression for longer duration camshafts.
Look around for dynamometer charts showing what people have built, and the power that was made.
OST Cyl head porting, -
viewtopic.php?f=22&t=300Building a great engine takes knowing the end... before you begin
Enjoy Life... its the only one you get!